The present invention relates to an apparatus and method for attaching an undercover to the underside of a floor panel of a car body. In particular, the present invention relates to an undercover attaching apparatus and method using studs fixed at predetermined positions on the underside of a floor panel of a car body, mounting holes formed in an undercover to receive the respective studs therein, and stud-engaging fasteners attached to the undercover in respective mounting holes.
It is well known to attach an undercover to the underside of a floor panel of a car body, for example, as disclosed in Japanese Utility Model Laid-Open No. 59-129676. In one technique of attaching an undercover to the underside of a floor panel of a car body, a plurality of threaded studs are fixed at predetermined positions of the underside of the floor panel, and a plurality of mounting holes are formed at predetermined positions of the undercover to receive the respective studs therein. Then, the undercover is positioned to the underside of the floor panel to insert the studs into the corresponding mounting holes, and nuts are screwed onto the respective studs with a tool or the like to complete an operation for attaching the undercover to the underside of the floor panel. This operation is troublesome and time-consuming because of the need for fastening a number of nuts to the studs over a large area of the undercover.
Further, when the undercover is attached to the underside of the floor panel by tightly screwing the nuts onto the threaded studs to prevent the undercover from dropping off, a fastening stress is concentrated on the fastened regions. The undercover is commonly a panel made of plastic material, which tends to expand and contract due to temperature changes during engine running and cooling down. Since the undercover is tightly fastened by the nuts at predetermined positions, it is subject to being distorted by thermally-induced stress around the fastened regions. This problem could be avoided if reliable attachment of an undercover could be achieved while allowing the attached undercover to be displaced along the underside of the floor panel to permit thermal expansion and contraction.
Japanese Utility Model Laid-Open No. 62-59311 (Japanese Utility Model Publication No. 3-19603) discloses an attaching assembly for attaching a panel such as an insulating panel, but not an undercover. In this attaching assembly, a tubular member is disposed around a stud in advance to position a panel, and a clip is engaged with the stud, so that the clip can be coaxially attached to the stud to maintain a high fixing force stably. If this attaching assembly were used to attach an undercover, it would be necessary to perform a troublesome operation of attaching a plurality of tubular members to corresponding studs in advance, and there would be no assurance of avoiding thermally-induced distortions.
Japanese Utility Model Laid-Open No. 7-41035 (Japanese Utility Model Registration No. 2584386) discloses a two-component clip for attaching a flexible panel such as a trim panel to a car body. In this clip, a first component has a hollow shank into which a hollow base of a second component is previously fitted to assemble the first and second components together, and the resulting assembly is inserted into and attached to the flexible panel from one side thereof. If this clip were applied to an undercover, however, it could not be inserted into the undercover from one side thereof, because the undercover has a high rigidity and is different from a flexible trim panel.
Japanese Utility Model Laid-Open No. 8-001091 (Japanese Utility Model Registration No. 2577997) discloses a two-component clip for attaching a panel to a car body. This clip comprises a male component with a flange and a female component with a flange. The male and female components are inserted into a mounting hole of the panel from opposite sides of the panel, respectively, to couple them together so as to clamp the panel therebetween. Then, the clip is engaged with a stud to fix the panel to the car body. There is no suggestion in Japanese Utility Model Laid-Open No. 8-001091 of applying this clip to the attachment of undercovers. In addition, Japanese Utility Model Laid-Open No. 8-001091 does not include any suggestion of a structure that would avoid thermally-induced distortion.